Fibroblast growth factors (FGF) are a family of more than 20 structurally related proteins with a variety of biological activities. Their main receptors, the fibroblast growth factor receptors (FGFR1, FGFR2, FGFR3 and FGFR4), are a family of receptor tyrosine kinases that bind FGF and are involved in processes of cell proliferation and differentiation. Deregulation of FGFR signaling networks is implicated in a number of pathophysiological conditions, including many types of human cancers.
“Fibroblast Growth Factor Receptor 4” or “FGFR4” is known to regulate proliferation and antiapoptosis and is expressed or highly expressed in many cancers. See, e.g., Dieci et al. 2013, Cancer Discovery, 0F1-0F16. Studies have shown that expression of FGFR4 is predictive of a more aggressive phenotype of the cancer, and knockdown or reduction of FGFR4 expression serves to reduce proliferation and promote apoptosis. See, e.g., Wesche et al. 2011, Biochem J 437:199-213.
For example, FGFR4 expression or overexpression is associated with cancer aggressiveness in gastric cancer (Ye et al. 2011, Cancer, 5304-5313), prostate cancer (Xu et al. 2011, BMC Cancer, 11; 84), sarcoma such as rhabdomyosarcoma (Taylor V I et al. 2009, J Clin Invest, 119(11):3395-3407), skin cancer such as melanoma (Streit et al. 2006, British J Cancer, 94:1879-1886), liver cancer such as cholangiocarcinoma (Sia et al. 2013, Gastroenterology 144:829-840) and hepatocellular carcinoma (French et al. 2012, PLoS ONE 7(5): e367313; Miura et al. 2012, BMC Cancer 12:56; Chiang et al. 2008, Cancer Res 68(16):6779-6788; Sawey et al. 2011, Cancer Cell 19:347-358), pancreatic cancer such as pancreatic intraepithelial neoplasia and pancreatic ductal adenocarcinoma (Motoda et al. 2011, Int'l J Oncol 38:133-143), lung cancer such as non-small-cell lung cancer (Fawdar et al. 2013, PNAS 110(30):12426-12431), colorectal cancer (Pelaez-Garcia et al. 2013, PLoS ONE 8(5): e63695; Barderas et al. 2012, J Proteomics 75:4647-4655), and ovarian cancer (Zaid et al. 2013, Clin Cancer Res 19:809-820).
Clinical development of several FGFR inhibitors have confirmed their utility as antitumor agents. Dieci et al. 2013, Cancer Discovery, 0F1-0F16. However, new agents are needed that are useful to target FGFR, and FGFR4, in particular.